Excitonic signatures in the optical response of single‐wall carbon nanotubes

Abstract

The optical properties of single-wall carbon nanotubes (SWNTs) are dominated by the excitonic character of the transitions even at room temperature. The very peculiar properties of these excitons arise from both the one-dimensional (1D) nature of carbon nanotubes and from the electronic properties of graphene from which nanotubes are made. We first propose a brief qualitative review of the structure of the excitonic manifold and emphasize the role of dark states. We describe recent experimental investigations of this excitonic structure by means of temperature dependent PL measurements. We investigate the case of upper sub-bands and show that high-order optical transitions remain excitonic for large diameter nanotubes. A careful investigation of Rayleigh scattering spectra at the single nanotube level reveals clear exciton-phonon side-bands and Lorentzian line profiles for all semi-conducting nanotubes. In contrast, metallic nanotubes show an ambivalent behavior which is related to the reduced excitonic binding energy.Schematic of the exciton manifold in single-wall carbon nanotubes.

All‐optical structure assignment of individual single‐walled carbon nanotubes from Rayleigh and Raman scattering measurements

“…Except for the GLB, the other subbands consist of a set of nearly parabolic bands. Interband absorption across conduction and valence subbands of the same index i is dominated by particularly strong excitonic transitions 9–11, labeled M ii and S ii for M‐ and S‐SWNTs, respectively. Noteworthy, excitonic effects persist in M‐SWNTs, with lower exciton binding energies owing to screening by the low energy excitations across the GLB 12–15.…”

Intraband and intersubband many-body effects in the nonlinear optical response of single-wall carbon nanotubes

“…The possible geometries of these hollow cylinders, known as chiral species, give rise to a large variety of electronic properties that are uniquely related to their structure 1 . The electronic and optical properties of carbon nanotubes reflect large electronic correlations leading for instance to the formation of strongly bound excitons, even at room temperature 2,3 . At higher excitation densities, electronic correlations give rise to a number of new signatures related to the exciton-exciton interactions, including exciton-exciton annihilation 4 or the formation of bi-excitons 5 or trions 6 below the S 11 excitonic transition.…”

Strong reduction of exciton-phonon coupling in single-wall carbon nanotubes of high crystalline quality: Insight into broadening mechanisms and exciton localization

“…The narrowing of the PL line of L-SWNTs is due to a weaker effective exciton-phonon coupling subsequent to a weaker localization of the exciton. These results suggest that exciton localization in SWNTs not only arises from interfacial effects, but that the intrinsic crystalline quality of the SWNT plays an important role.Photoluminescence (PL) emission in semiconducting carbon nanotubes arises from exciton recombination [1][2][3] and has been extensively studied in view of possible applications in opto-electronics, bio-imaging or photovoltaics [4][5][6][7]. Observation of photon antibunching in the near infrared [8,9] suggests that SWNTs are also promising single-photon sources for the implementation of quantum information protocols.…”

“…Photoluminescence (PL) emission in semiconducting carbon nanotubes arises from exciton recombination [1][2][3] and has been extensively studied in view of possible applications in opto-electronics, bio-imaging or photovoltaics [4][5][6][7]. Observation of photon antibunching in the near infrared [8,9] suggests that SWNTs are also promising single-photon sources for the implementation of quantum information protocols.…”